apparatus for making dry ice

[Natrix]

This device is connected to a CO2 cylinder. An injection time of 1 minute produces a diameter 50 x 22 mm dry ice pellet. Looks like it can be easily build at home.

[lugh]

This is normally done with an orifice and a heavy duty canvas bag, but since the carbon dioxide has to expand to cool enough to form solid carbon dioxide, 90% of the carbon dioxide ends up in the air    Ventilation is required since asphyxiation is a definite hazard, the main application of this type of apparatus for our purposes is in preparing finely powdered carbon dioxide for a Grignard  

[biffman]

If I remember correctly when I had to re-order the CO2 cylinder in the lab that we used for making dry ice I had to specify that it was supposed to be the type that had a tube inside.  Apparently the tube goes down into the bottom of the cyclinder ensuring that it is liquid CO2 that is being used to expand into gas then freezing.  If we just used the regular tank of CO2 without the dip tube (or whatever it was called) ice wouldn't be formed properly because we were only expanding the gas that was found at the top of the liquid in the cylinder which wouldn't than get cold enough to freeze.  Although it might be because of the type of ice maker that we were using.
  Just a thought for anyone who is going to be making their own dry ice (although it is cheap to buy).
  Ask for the cylinder with the internal tube in it.

[baalchemist]

One can also turn the tank upside down to get the liquid close to the valve.

[biffman]